The present invention generally relates to tape cassettes having a reel support structure, and more particularly to a tape cassette which accommodates tape reels having reel flanges and is provided with a reel support structure for rotatably supporting the tape reels.
A conventional tape cassette which is commonly available comprises a cassette case which rotatably accommodates a pair of reel hubs. A leader tape is connected to each end of a magnetic tape, and each leader tape is fixed to the corresponding reel hub so that the magnetic tape may be wound on the reel hubs. When the magnetic tape moves in such a tape cassette, the magnetic tape is paid out of one tape roll on one reel hub and is taken up on the other tape roll on the other reel hub. Thus, upper and lower surfaces of each tape roll, which are formed by upper and lower edges of the magnetic tape, respectively make contact with inner surfaces of the cassette case as the tape roll rotates. Accordingly, in this type of a tape cassette, synthetic resin sheets having a small frictional resistance are adhered on the inner surfaces of the cassette case. As a result, the upper and lower surfaces of each tape roll make contact with the synthetic resin sheets as the tape roll rotates, and the frictional resistance between the upper and lower surfaces of the tape roll and the synthetic resin sheets is kept to a minimum.
However, each tape roll makes contact with the synthetic resin sheets, over the entire area of the upper surface thereof and over the entire area of the lower surface thereof. The area over which one tape roll is in contact with the synthetic resin sheets depends on the diameter of the tape roll, however, the two tape rolls are in constant contact with the synthetic resin sheets over a relatively large area. Therefore, although the frictional resistance between the upper and lower surfaces of the tape rolls and the synthetic resin sheets as the tape rolls rotate is reduced due to the small frictional resistance of the synthetic resin sheets, a frictional resistance which cannot be neglected still exists between the upper and lower surfaces of the tape rolls and the synthetic resin sheets. The existence of such a frictional resistance interferes with the smooth and stable rotation of the tape rolls, and accordingly interferes with the smooth and stable movement of the magnetic tape.
On the other hand, another type of tape cassette has been developed. This other type of tape cassette comprises a cassette case which accommodates a pair of reels each having a reel hub provided with upper and lower reel flanges, instead of accommodating the reel hubs which are not provided with the reel flanges. When this other type of tape cassette is molded from a transparent resin, the reel flanges are visible through the cassette case from the outside. Hence, it is possible to improve the external appearance and give the tape cassette a high-grade appearance, by molding the reel flanges from a synthetic resin and forming metal or metal-like prints on the reel flanges. In addition, by putting colors, designs, or the like on the reel flanges, it is possible to give the tape cassette a surprisingly fine appearance which is unknown in the conventional tape cassette.
However, even in this other type of tape cassette, the reel flanges of each reel make contact with the inner surfaces of the cassette case. Thus, synthetic resin sheets having a small frictional resistance are adhered on the inner surfaces of the cassette case. As a result, the reel flanges of each reel make contact with the synthetic resin sheets as the reel rotates, and the frictional resistance between the reel flanges of each reel and the synthetic resin sheets is kept to a minimum. However, each reel makes contact with the synthetic resin sheets, over the entire area of the upper reel flange thereof and over the entire area of the lower reel flange thereof. Therefore, although the frictional resistance between the upper and lower reel flanges of the reels and the synthetic resin sheets as the reels rotate is reduced due to the small frictional resistance of the synthetic resin sheets, a frictional resistance which cannot be neglected still exists between the upper and lower reel flanges of the reels and the synthetic resin sheets. The existence of such a frictional resistance interferes with the smooth and stable rotation of the reels, and accordingly interferes with the smooth and stable movement of the magnetic tape. Consequently, there is a problem in that a large torque is required to rotate the reels.